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mitigation plan, and shall meet the following criteria: <br />a. The watercourse alteration shall comply with the standards in current <br />use and the standards of the Washington Department of Fish and Wildlife Water Crossing <br />Design Guidelines Manual 2013 or as amended. <br />b. The watercourse alteration shall not cause adverse impacts to fish, <br />confine the channel or floodplain, or adversely affect riparian habitat (including <br />downstream habitat). <br />c. Maintenance dredging of watercourses shall be allowed only when <br />necessary to protect public safety, structures and fish passage and shall be done as <br />infrequently as possible. Long-term solutions such as stormwater retrofits are preferred <br />over ongoing maintenance dredging. <br />d. Stormwater runoff shall be detained and infiltrated to preserve the <br />existing hydrology of the watercourse. <br />e. All construction shall be designed to have the least adverse impact on <br />the watercourse, buffer and surrounding environment. Construction shall minimize <br />sedimentation through implementation of best management practices for erosion control. <br />f. As a condition of approval, the Director may require water quality <br />monitoring for stormwater discharges to streams, and additional treatment of stormwater <br />if water quality standards are not being met. <br />g. Where allowed, piping shall be limited to the shortest length possible as <br />determined by the Director to allow access onto a property. <br />h. Where water is piped for an access point, those driveways or entrances <br />shall be consolidated to serve multiple properties where possible, and to minimize the <br />length of piping. <br />i. Piping shall not create an entry point for road runoff, create downstream <br />scour, or cause erosion or sedimentation. <br />j. Water quality must be as good or better for any water exiting the pipe as <br />for the water entering the pipe, and flow must be comparable. <br />C. MITIGATION STANDARDS. <br />1. The following shall be considered the minimum standards for approved <br />mitigation projects: <br />a. Maintenance or improvement of stream channel habitat and dimensions <br />such that the fisheries habitat functions of the compensatory stream meet or exceed that <br />of the original stream; <br />b. Bank and buffer configuration restored to an enhanced state; <br />c. Channel, bank and buffer areas replanted with native vegetation that <br />improves upon the original condition in species diversity and density; <br />d. Stream channel bed and biofiltration systems equivalent to or better than <br />in the original stream; <br />w:\Legislative Development\Critical Areas update 2-25-20 <br />MD:bjs Review and analysis by Barbara Saxton Page 32 of 87 <br />